title: Effects of natural hybrid and non-hybrid Epichloë endophytes on the response of Hordelymus europaeus to drought stress.
abstract: Interspecific hybrid endophytes of the genus Epichloë (Ascomycota, Clavicipitaceae) are prevalent in wild grass populations, possibly because of their larger gene variation, resulting in increased fitness benefits for host plants; however, the reasons are not yet known. We tested hypotheses regarding niche expansion mediated by hybrid endophytes, population-dependent interactions and local co-adaptation in the woodland grass Hordelymus europaeus, which naturally hosts both hybrid and non-hybrid endophyte taxa. Seedlings derived from seeds of four grass populations made endophyte free were re-inoculated with hybrid or non-hybrid endophyte strains, or left endophyte free. Plants were grown in the glasshouse with or without drought treatment. Endophyte infection increased plant biomass and tiller production by 10-15% in both treatments. Endophyte types had similar effects on growth, but opposite effects on reproduction: non-hybrid endophytes increased seed production, whereas hybrid endophytes reduced or prevented it completely. The results are consistent with the observation that non-hybrid endophytes in H. europaeus prevail at dry sites, but cannot explain the prevalence of hybrid endophytes. Thus, our results do not support the hypothesis of niche expansion of hybrid-infected plants. Moreover, plants inoculated with native relative to foreign endophytes yielded higher infections, but both showed similar growth and survival, suggesting weak co-adaptation.
authors.affiliation: Plant Ecological Genetics, Institute of Integrative Biology, ETH Zürich, Universitätstrasse 16, CH-8092, Zürich, Switzerland.|Department of Biology, University of North Carolina Greensboro, 321 McIver Street, Greensboro, NC, 27412, USA.
authors.forename: Martina
authors.initials: M
authors.lastname: Oberhofer
authors.affiliation: Plant Ecology, Institute of Integrative Biology, ETH Zürich, Universitätstrasse 16, CH-8092, Zürich, Switzerland.
authors.forename: Sabine
authors.initials: S
authors.lastname: Güsewell
authors.affiliation: Plant Ecological Genetics, Institute of Integrative Biology, ETH Zürich, Universitätstrasse 16, CH-8092, Zürich, Switzerland.
authors.forename: Adrian
authors.initials: A
authors.lastname: Leuchtmann
mesh_terms: D018533:Biomass; D055864:Droughts; D060026:Endophytes / Q000235:genetics; D055329:Epichloe / Q000235:genetics*; D014644:Genetic Variation; D006824:Hybridization, Genetic; D055328:Neotyphodium / Q000235:genetics; D006109:Poaceae / Q000502:physiology*; D036226:Seedlings; D013312:Stress, Physiological; D013559:Symbiosis / Q000235:genetics*
keywords: drought adaptation; hybrid endophyte; inoculation; mutualism; niche expansion; woodland grass